


Sins of Mortals

by Maddie_writes_stuff



Category: Harry Potter - J. K. Rowling
Genre: AU, Enemies to Friends to Lovers, F/M, Marauders, Marauders Era (Harry Potter), Multi, Reader-Insert, Slow Burn, Slytherin! reader, The Marauders - Freeform
Language: English
Status: In-Progress
Published: 2019-05-29
Updated: 2019-06-02
Packaged: 2020-03-29 12:00:47
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 4,180
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19019506
Author URL: https://archiveofourown.org/users/Maddie_writes_stuff/pseuds/Maddie_writes_stuff
Summary: you disliked Gryffindors, especially that no good womanizer Sirius Black. you hated him even before you properly met him. But now that he has introduced to you... you don’t dislike him, you hate him.





	1. troublesome encounters

you had never met the famous Sirius Black. But that didn’t mean you hadn’t heard of him. He was practically all anyone could talk about. You thought it was odd how obsessed everyone was with him. Especially considering he was a Gryffindor, and you were in Slytherin. Snape’s talk about the Marauders was never-ending, but at least Snape would talk about them all equally, the girls in your house where the worst. 

They talked about him nonstop, what they would do to him if they got him alone, and how good he looked both in and out of his uniform. It was gross honestly, you were supposed to hate Gryffindors, especially when those same Gryffindors threw stink bombs in the common room and filled the bathrooms with Red and Gold slime monsters that ate your hairbrush. Everyone seemed ready to forgive Sirius for his misgivings just because he had a pretty face. You would admit that he was attractive, but that wasn’t an excuse, at least not to you. 

“what kind of conditioner do you think he uses?” Sam Lithermyn sighed looking dreamily over to the Gryffindor table.

“Whatever it is it smells like Strawberries,” Jane Hollyberry said also looking at Sirius.

“Sometimes I think he might not be human, he’s prettier than any human I’ve ever met,” Sam spoke again. You huffed and tried to ignore them both. but after a minute you could help but follow their gazes toward Sirius. He was pretty, the morning sunlight glinted off his dark glossy hair, his cheekbones and jawline were both sharp enough to cut glass. And his eyes, deep and green with flecks of gold seemed to see the whole room. You could see why Sam didn’t believe he was human, you could hardly believe it yourself. You blinked and shook your head to clear it. It was no wonder he had slept with half the girls in Hogwarts.

“Merlin, Sam! He’s coming over here look!” Jane hissed dropping her eyes to her breakfast. you looked up Sirius black was sauntering over to the Slytherin table. Sirius stopped before you.

“Hello, (y/n),”

“what the hell do you want Black?” you snapped, your wand already in your hand. it wasn’t every day someone crossed the great hall to see you.

“easy there love,” he chuckled “why don’t we go on a walk I want to talk to you”

“I think I’ll stay right here thanks,”

“fine, you see the After the Slytherin v. Gryffindor quidditch match we’re gonna have a little victory party-” you cut him off right there

“what makes you think you’re going to win aye? Slytherin is going to crush-” it was his turn to cut you off.

“Listen, it doesn’t matter who wins, Friday, after the Match, party in the Gryffindor tower, you in?” you could see how annoyed he was so that begged the question, why the hell was he doing this?

“No,” you said without pausing to think.

“why not?”

“I’d be a shit time, I don’t know anyone there,”

“Okay listen, I’m not supposed to tell you this but since you’re being difficult you see Aaron Mole over there? Redhead glasses,” he asked you looked behind him and saw the boy he was talking at you. “has a big crush on you begged me to ask you to the party so he can flirt with you, so how ‘bout you do me a favor,”

“Nope,” you said shrugging, he groaned.

“give me one good reason why not?”

“I already have plans,” you said, which was true, not that you could ever tell him what you were doing. Sirius opened his mouth but before he could speak Jane cut him off.

“I could take (y/n)’s place if you need a Slytherin girl to shake things up,” she offered. Sirius shot her a quick smile,

“Don’t think that I don’t want you there baby but I really need (y/n) to come for my pal.” his angry eyes fell back to you “Almost time for class aye? Want me to walk you to class?”

“I can walk my own damn sel-”

“perfect I’ll carry your books,” he said trying to grab your book bag but you snatched it out of his way. Your heart skipped a beat at the thought of Sirius of all people seeing what you had in that bag.

He talked your ear off as he walked with you to the potions room

“what is so important that you can’t stop by just for one butterbeer?”

“I’m not coming, so drop it,” you snapped. That finally made him leave you alone, until lunch that is. 

“Okay so you’re not coming to the party, fine whatever, but you’re coming to the Match right?” he asked coming to a stop beside you.

“Hello to you Sirius,” you said rolling your eyes. “and no I’m not planning on going to the match.” everyone would be out of the castle, It was the only time no one would be looking for you. 

“The hell, you aren’t! It’s the First Game of the year and It’s Slytherin Vs. Gryffindor, What do you mean? You can’t miss that!”

“I can and I will, I told you I have plans,” you said hotly. “Besides why do you care so much,”

“you are unbelievable! And Moles is a good friend I’d do anything for him!” he shouted. You looked at him skeptically.

“you owe him a favor don’t you.”

“perhaps, Anyway, what the fuck are you doing that makes you think you can miss the Match,”

“Oh sod off you only want me to come so you can force me to sit next to Moles or something,”

“Maybe I want you to come and cheer for me, you know; wear my scarf wave a Gryffindor banner, the works”

“like I’d ever cheer for you, you’re a Gryffindor and a massive prick I don’t even know why I’m talking to you.” you huffed and sat down at the Slytherin table.

“Stop Harassing the girl Black unless you want me to call the prefects,” you turned away from Sirius to see Severus Snape. You didn’t necessarily dislike Severus, but he did have a nasty habit of losing the house points. Sirius shot you with a finger gun

“See you, latter Baby,” he spun and ran off to the Gryffindor table.

“I’m not your Baby!” you shouted at him. You weren’t used to being the center of attention, but when Sirius looked at you, everyone did. Sam, Jane, and all the girls for that matter swarmed you asking you what Sirius had wanted with you.

“looked like he was flirting, the way he was looking at you,” Jane hissed looking at you with wide eyes. she almost looked hopeful. As if Sirius flirting with you was the same as him flirting with her. 

“Black would never go so low as to flirt with a Slytherin,” you said rolling your eyes.

“Didn’t he get with Violet?”

“Christ Sam, I would hook up with Violet the girl is hot,”

“does it really matter?” you asked, “he is a prick and I want nothing to do with him.” but just because you didn’t want anything to do with him didn’t mean he wanted nothing to you. 

You were sitting curled up on one of the black leather couch next to the fireplace in the Slytherin common room. You pretended to be focusing on the DADA homework you had balanced on your knees. In reality, you were waiting patiently to be left alone. You where normally the last one to go to bed. Finally, Glen Hourshin yawned and stood up.

“go to bed soon (y/n),”

“I will, goodnight Glen,” you said watching him leave, you tucked away “Dealing With Trolls, Not just the Ones you are related too.” and reached for a small leather book in your bag. The book your mother had given you. But just as your fingers touched the unnaturally cool spine, you heard a voice.

“Thank Merlin, I thought he’d never leave.” you recoiled from the book and whirled to see Sirius appearing out of thin air.

“what the hell are you doing here?” you hissed drawing your wand.

“well, I figured that the only reason you had for missing the game is your grades. So I came here to help you with homework,”

“like I would need help from a Git like you. If anything you would come to me for help,” you snapped.

“Have you mastered the Invisibility charm the way I have?” he asked cockily. that was true enough, you could make marbles and buttons disappear no problem but anything larger was tricky. Then you remembered you hadn’t heard him speak. 

“oh you’re probably shit at the Invisibility charm, but doesn’t matter when you have an invisibility cloak,” you said triumphantly, proud of yourself to have figured it out. Sirius’s smile faltered. You had him now. “that’s the one from Zonko’s joke shop isn’t it?” you pressed taking a step towards him. For whatever reason, this comment seemed to relax him.

“so what are you working on now? You finished the Defense homework so what now?” he asked changing the subject, he fell gracefully on the couch beside where you had been sitting.

“why are you really here? You could be kicked out of Hogwarts for this you know,” you said sitting beside him cautiously. The firelight did something strange to his eyes, making them flash for a second. Suddenly heat was rising from your chest to your face. You hatted yourself for the fact that just sitting beside him made you blush. Again you were stuck with how handsome he was. There was a stray hair hanging in front of his nose. you were surprised by the urge to move the hair back in place maybe run your fingers through his long black hair, maybe pull him close and see if his lips were as soft as they looked. You shook your head, clearing your mind. you would sooner die than kiss Sirius 

“I want to show you how far I’m willing to go to get you to come.” his voice was like velvet. You rolled your eyes

“Moles really has some dirt on you huh?”

“It will take five minutes, you come and let Moles flirt with you a little bit then tell him you aren’t interested then you can leave to go out and do your thing,” he whined like a toddler. You realized with a wave of satisfaction that you were probably the first girl to ever tell him no.

“I’ve never talked to Moles, I might want to talk to him for a while, and for that I need time.” you teased. Sirius looked like he was ready to strangle you. He mumbled something about Slytherins all being the same

“Look, Sirius, I promise I’ll go to the next party you throw, or better yet I’ll go on a date with Moles if you set it up, just not Friday,” you said. 

“I can’t just set up a date you aren’t supposed to know!” he said you could see the annoyance building,” You needed him to leave before either of you started throwing spells. 

“goodnight Sirius,” you said in a bored voice standing up. Sirius glared and threw on his invisibility cloak. Sirius’s disembodied voice called out to you.

“I’ll see you in the morning (y/n) and I swear by Merlin’s Beard I’ll convince you to come.” you could hear him stop away and Slam the door. You wanted to pull the book out right there but there was a chance he was still here. You picked up your bag and went to your dorm room you pulled the covers over your head and took notes while trying to stay as quiet as possible. 

Normally you wouldn’t risk reading this book when there were other people around but at least you knew Sirius couldn’t get in here. It would be just your luck to have him follow you into the dungeons instead of going to the quidditch match. you supposed that it was a bit hypocritical of you to get mad at him for sneaking into your common room, he could get kicked out of Hogwarts if you ratted him out. but if he caught wind of what you were up too, you would be sent to Azkaban.


	2. the games we play

**Summary for the Chapter:**

> paranoia isn’t exactly a desirable feeling, but you can’t help but be on your toes when Sirius Black is following you begging for your attention. It is only natural to be cautious, after all, who knows what he might see if he peeks over your shoulder.

**Notes for the Chapter:**

> I got called a "blue balling cock tease" for ending this chapter where I did so there's that

It was Thursday, only one day left for you to prepare. Which made it all the more annoying that Sirius was following you like a lost puppy. You couldn't get a moment alone it seemed. If Sirius wasn't up your ass trying to figure out your plans for Friday, then Sam or Jane would by your side, or up your ass more accurately, trying to learn what Sirius saw in you. You honestly didn't get it either. You had promised to go out on an actual date with Moles.

But Sirius refused, you knew he wasn’t supposed to have told you about the crush thing but you also knew that wasn’t the real reason he was doing this. the whole thing had taken on a new life for Sirius. This was his pride on the line now, the whole of Hogwarts knew Sirius was trying to get you to go to the party and you were saying no. He had to succeed.

it was funny, you could see him go through the five stages of grief he had moved past denial and anger to bargaining. He tried to literally bribe you with a pile of gold large enough to make your jaw drop. Then he offered to cut his hair, his precious hair, that hadn't done it either. You knew he was desperate when he told you that he would wear a Slytherin scarf to the game. As much as you would have loved any of those things, you had to say no. 

When Sirius didn't accost you the moment you walked into the great hall Thursday morning, you felt odd. You would almost say you missed him only, you hated Sirius. It was like someone pulling a thorn out of your side. Freeing, that was the word for it, you felt free. You didn't see Sirius all day and as much as you wanted to spend time thinking about what Sirius was up to, you didn't care.

There were more important things to do. Your fingertips were blue and your hands were shaking by the time you were done studying. You hated that damn book. You swore the thing got colder the longer you held it. You supposed that was a small price to pay for learning something like this. You rubbed your hands together as you exited the girl's bathroom, it wasn't classy but it was one of the only places you could be assured privacy. Suddenly two warm hands where holding yours.

“you're freezing baby,” Sirius purred, he brought your hands to his face and blew hot air on your icy fingers. The sunlight from outside streamed through the windows making Sirius's gorgeous green eyes flash. Goosebumps rose on your arms, in the best way possible.

“It's been a while hasn't it Sirius,” you said matching his quiet volume.

“did you miss me?” he asked pulling you closer. He was so close, you could smell the spicy cinnamon of his cologne. It was slightly addicting.

“maybe,” you admitted. Although, the voice almost didn't sound like yours.

“then you should come to the party tomorrow, and I promise I'll make up for lost time.” his voice rumbled deep in his chest.

“I'd love to Sirius, but I can't,” you said pulling your hands out of his. “also did you really think you could flirt with me until I gave in?” you asked glaring at him.

“uh maybe?” he flashed you a bright smile and you rolled your eyes. 

“Sirius I'll compromise with you, I'll go to the game-” his eyes lit up and he started to talk. “-for five minutes.” you finished 

“(y/n) that isn't enough time to even start the game!”

“Look I'll either go for five minutes, maybe even talk to Moles, if I see him. Or I'll just not go, I don't owe you anything,” you snapped. Sirius thought about it for a second.

“Fine, deal. You come AND talk to Moles at the game and I'll leave you alone for the rest of the bloody year. If that's what you want,” he said with a wink. You rolled your eyes and stuck out your hand.

“Deal, shake on it,” you said, scowling and sticking your hand out. You couldn't believe how much you were giving up, five whole minutes, someone would notice you where gone

“I think this is the type of deal that needs to be sealed with a kiss wouldn't you say?” he asked cheekily before you could curse him out he grabbed your hand, shook it once then took off racing down the halls.

“A man's word is his bound (y/n) I'll see you tomorrow!” he called behind his shoulder, not slowing down. You sighed and walked to your next class fuming.

You woke up early the next morning, your whole body shaking. You were freezing and terrified though you couldn’t tell why. when you through back the covers to your dorm bed you saw the book, frozen to the center of the bed. A thick black, leather cover. Silver ink spelled out evil texts in old Latin. Even you weren't entirely sure what the cover said, but your mother had warned you never to let anyone else see the book. You picked the book up by its spine and slid it into your back into your bag. 

You wrapped the blanket around your solders. You wanted to go to sleep even if it was just for a few more minutes, but sleep evaded you. You had been preparing for today for months, but now that today was finally here. You weren't ready. You felt like you were going to throw up but then you thought about writing your mother telling her you couldn't do it, and you thought about what she would react.

Another shiver ran down your spine. You sat on the bed while the other girls woke up and got ready for the day. None of them paid attention to you as they fixed their hair and dawned their robes. Slowly you followed suit pulling on the Slytherin uniform and brushed your hair so it looked halfway decent.

“(y/n) are you okay?” Sam asked she touched your shoulder making you flinch.

“I'm fine Sam I'm just, on edge a little bit,” you explained. You could have sworn you had put that damn book away before you fell asleep. Maybe you were losing your mind. Or maybe the book had crawled its way into bed with you. You didn't know which option scared you more.

“worried about the match,” you said seeing that she didn't buy it you continued. “I bet Colin Norwalk six gillions that Slytherin will win and catch the snitch, you know Tom is a demon on that broom. Colin seems to think that Gryffindor has any chance he bet they would scrape by a vicorty, ” you said. Colin was taking so many bets today you doubted that he would remember if you had a wager with him or not, that is, If Sam bothered to ask. Sam smiled at you.

“Colin better get ready to say goodbye to his money, Slytherin is going to pulverize those lion bastards. Severus says he made a special pregame potion for the whole team, no way we'll lose!” she cheered happily, the cry was quickly picked up by the others at your table 

“you don't mean Liquid Luck do you?” you asked trying to sound concerned, the truth was you could use a little luck yourself. Sam shook her head.

“that shit's illegal Sev knows that but he said it was something, similar.” you nodded an frowned. You would have to do this on your own then. You supposed that was the point of this whole thing. Your mother's way of testing you. You thought of the hidden room you had found early in your first year, and the bottles you had stored down there. You hated that room, but after tonight you would never have to see it again. If everything went right that was. And things so rarely did.

You hadn't realized you had exited the dorm room but here you were outside next to Sam and Jane walking to the quidditch field the cold October air blew harshly rustling your clothing and reminding you that you had forgotten your scarf and your coat. You shuddered, but the breeze was nothing compared to the freezing bed you had woken up to this morning. You hated that book but again, tonight would be the end of it, the book could be returned to your mother's private bookshelf, where it would stay, slowly freezing the wood beneath it until it was time for your next test. You had started to enter the stands when you heard your name being called, then a hand fell on your shoulder.

You whirled ready to attach, but it was just Arthur Moles. You relaxed a little

“Hey (y/n)!” he said you could hear the nervousness in his voice.

“Hello Arthur, are you excited for the game?” you asked politely.

“yeah it'll be fun, Sirius said you weren't going to the party,” he said making you wince.

“No. afraid not, Just don't have the time,”

“Shame I was hoping you would be there so we could talk,”

“I can't imagine that a Gryffindor party is a good place for conversion,” you teased making Moles blush.

“I like you,” he blurted “And I want to get to know you better would you like to go on a date with me?” he shouted. But you weren't looking at him. Instead, you were focused on Sirius Black who had caught sight of you and was running over. “I'm free Wednesday if you want to go to Hogsmeade with me?” you had never seen someone's face go so red.

“yeah sure sounds great,” you said not fully aware of what you agreed to. Sirius was close enough for you to make out the red and gold stripes he had painted on his face. The wind blew again chilling you to the bone. Moles notice you shiver 

“Oh gosh, you must be freezing!” Moles said taking a step closer making you take a step back.

“I thought I would be fine like this but I think I'm going to run back to the castle and grab a jumper,” you said turning away from Moles. and Sirius.

“do you want to borrow mine?” he offered

“no thank you,”

“oh, want me to come with you then?”

“No, go ahead and get a seat I'll see you around,” you called already running away from him. You had no idea how much time you had. Quidditch was like that, you hurried back into the Slytherin dungeon than to the girl's dorm room. Not your own dorm, but the room directly to the left. You fidgeted nervously in front of the door. Then, before you could lose your nerve, you walked into the room confidently. Luckily no one was there. But you didn't relax ever since Sirius had come in with that invisibility cloak you couldn't shake the feeling that someone was watching you.

You knew your mother had a charm for detecting if someone was following you. even so, you didn’t bother asking for it. She would probably tell you that it was a good thing to be cautious. and it was a draining charm to perform you could only do it once or twice before you passed out. So there you were, letting nothing but fate protect you. 

You looked around the room and found the mirror you where looking for. it was ornate and large. stretching from the ground almost to the ceiling. with an intricate gold frame if you bothered to look at the frame you would see hundreds of tiny snakes interweaving and hissing at one another.

You had been a scared little first year trapped in the wrong dorm room when you had first found the mirror. Any second the rightfully owners of this room would walk in and, who knows what. The Slytherin upperclassmen scared you terribly that year. You had backed yourself up against the wall only to find the mirror wasn't just a mirror, you approached the confidently now and walked right through the glass onto a landing, overlooking a tightly wound set of spiral stairs going down deeper under the moat. You looked back at the room, which was visible as if you were inside the mirror looking out.

The room remained unchanged. “Lumos,” you whispered lighting your wand there was no turning back now. You pulled the book from your bag and began your descent into the very depths of Hogwarts.

**Author's Note:**

> depending on how this does I'll be posting the second part soon.


End file.
